The present invention relates generally to ceramic casting cores used in the production of cast components. More particularly, in one embodiment of the present invention an integral ceramic casting core having a flat plate portion with apertures formed therein, and a plurality of rod members extending therefrom is utilized in an investment casting process to define the cooling passages and heat transfer pedestals in a cast gas turbine engine airfoil. Although the present invention was developed for use in the production of gas turbine engine components certain applications may be outside of this field.
Investment casting is a well-known technique for the production of superalloy blades and vanes for gas turbine engines, particularly those requiring an internal cooling scheme. In investment casting, a ceramic shell mold is formed around a wax pattern with one or more ceramic cores precisely positioned within the wax pattern, occupying the position of required holes and passages in the casting to be produced. The wax pattern is subsequently removed during a firing operation, while the mold and cores remain in place, thus providing a mold cavity. Molten metal is poured into and solidified in the cavity and the ceramic cores are chemically removed.
In many prior art investment casting systems, the ceramic cores are individually positioned and aligned in a predetermined manner by a skilled technician. The complexity of the cooling scheme geometry and the requirement for the precision location of the ceramic cores in order to reproduce the cooling scheme design in the cast component can be a very time consuming and expensive process.
Although investment casting techniques utilizing individual ceramic cores are suitable for producing many types of cast gas turbine engine components, the need remains for an improved ceramic casting core and method of use. The present invention satisfies this need in a novel and unobvious way.
One form of the present invention contemplates an integral ceramic casting core having a plurality of pin members extending therefrom and a plurality of holes formed therein for receiving a molten metal.
Another form of the present invention contemplates a casting core comprising: a substantially planar ceramic main body member having a first surface and a second surface and a thickness less than about 0.020 inches, the member having a plurality of spaced holes formed therein having a size of about 0.030 inches and adapted for receiving a molten metal therein; and a plurality of ceramic members having a nominal width of about 0.020 inches that are connected with the first surface, each of the ceramic members are disposed normal to the first surface.
One object of the present invention is to provide a unique ceramic casting core.
Related objects and advantages of the present invention will be apparent from the following description.